Moriarty wore a woman's face.
She was Root, with her wild eyes and the mixture of insanity, obsession, and cold calculation. Root, the root of all things, just as Moriarty had been the spider at the center of the web.
Harold had long-ago realized that Moriarty was everywhere, in all times and all places. It didn't matter how often he was vanquished. He would return, with a new guise, a new method, a new evil.
He saw the same malevolence and obsession stare out of the woman's eyes, and he recognized his old foe. Sherlock's old foe. As surely as Sherlock had helped the unassuming professor meet his death at the falls, the evil that had consumed him had spread and infected others. Other Moriartys.
People thought Elias was the greatest enemy, Elias and the network of men and women he commanded, even from prison, to do his bidding. But they were wrong. Moriarty was more subtle than that. Moriarty was in every shadow, in the background of every snapshot, never seen but always felt. Elias had his guns and his bombs, but Root, she could take down a city with a keystroke.
He had never even tried to explain to John. Perhaps some day—perhaps, if they lived to speak again. For now, knowing was all he could manage, knowing and calculating.
He needed John. If Moriarty was back again, he needed his partner more than ever before. He needed him like a brother. Like Sherlock.